The invention pertains to methodology and apparatuses associated with treating semiconductor substrates in liquid baths. In particular aspects, the invention pertains to methodology and apparatuses associated with determining if a protective coating on a semiconductor substrate receiving device has been compromised.
In modern semiconductor processing, it is frequently desired to insert semiconductive material wafers into liquid baths. Such baths can comprise chemicals which would be corrosive to metal parts. For instance, a bath comprising H2SO4:H2O2:H2O (6:1:1, by volume) at about 120xc2x0 C. is utilized for stripping photoresist as well as for cleaning organic materials from over semiconductive material substrates. As another example, H3PO4 (85%:15% H3PO4 to H2O, by volume) at about 160xc2x0 C. is utilized for etching Si3N4. In yet another example, dilute hydrofluoric acid (about 49% hydrofluoric acid in water (by weight)) is utilized to etch oxide.
Due to the corrosive nature of baths, like those above, relative to steel, apparatuses configured to retain semiconductive material substrates within a bath typically utilize non-steel materials for those portions of the apparatus that will be dipped within the bath. Such non-steel materials include, for example, quartz and Teflon(trademark). However, the non-steel materials can have structural disadvantages when compared to steel. Accordingly, it can be desirable to utilize steel for portions of a semiconductive substrate treatment apparatus that are dipped into a corrosive bath.
One method of utilizing steel for such portions of a semiconductive substrate treatment apparatus is to coat the steel with a protective coating, such as, for example, Teflon(trademark) (polytetrafluoroethylene or PTFE) or poly(vinylidene fluoride) (PVDF). The coating provides a barrier over steel portions of a semiconductor wafer treatment apparatus that are dipped within a corrosive bath. A problem occurring with such coatings is that semiconductor wafers can comprise sharp edges, and such edges can cut through the protective coatings to expose the steel material thereunder. The exposed steel material can then be corroded by the chemicals in a bath. The corrosion can pollute the bath and eventually destroy the structural integrity of the steel material.
It would be desirable to develop methods for identifying if a protective coating provided over a steel material has been compromised. It would be particularly desirable to develop methods which would identify a compromised protective coating before the structural integrity of an underlying steel material is destroyed by exposure to corrosive baths.
In one aspect, the invention includes an apparatus configured to measure an electrical conductivity between an insulatively coated conductive semiconductor substrate receiving device and a bath within which the device is submerged. Such measurement can determine if the insulative coating has been compromised.
In another aspect, the invention includes an apparatus comprising a semiconductor substrate receiving device with at least one extension configured to hold a semiconductor substrate within a liquid bath. The device is configured to have at least a portion of the extension at least periodically placed within the liquid bath. The extension comprises a conductive material at least partially coated with an insulative protective material. The insulative protective material is configured to protect the portion of the conductive material which is in the bath from physically contacting the liquid of the bath. The apparatus also comprises an electrode within the bath, and an electrical connection between the electrode and the conductive material of the extension. Additionally, the apparatus comprises a monitor configured to monitor a current flow state of a circuit comprising the electrode, conductive material of the extension, and liquid bath to determine if the circuit is in a closed state (which enables a current flow) or in an open state (which does not enable the current flow).
In yet another aspect, the invention includes methods for determining if a protective coating on a semiconductor substrate receiving device has been compromised.